SpinM1 excitations in deformed nuclei from self-consistent Hartree-Fock plus random-phase approximation

Abstract

We present a method to study spin magnetic dipole excitations in deformed nuclei within the quasiparticle random phase approximation based on self-consistent Hartree-Fock mean fields and residual interactions derived from the same effective two-body force. We perform a comprehensive study covering different Skyrme forces and various mass regions, and discussing the role of the mean field and of the residual interaction. An overall agreement with experimental data is obtained with the SG2 force. We study the systematics and the deformation dependence of the spin M 1 strength distributions of K ϭ1 ϩ excitations. It is found for the first time that the summed spin M 1 strength obeys a quadratic dependence on deformation in the two isotope chains studied,

Spin–isospin excitations and half-lives of medium-mass deformed nuclei

“…Our method consists in a selfconsistent formalism based on a deformed Hartree-Fock mean field obtained with a Skyrme interaction including pairing correlations in the BCS approximation. We consider in this paper the force SG2 [16] of Van Giai and Sagawa, that has been successfully tested against spin and isospin excitations in spherical [16] and deformed nuclei [17]. Comparison to calculations obtained with other Skyrme forces have been made in Refs.…”

“…The results correspond to the selfconsistent HF+BCS+QRPA calculations with the SG2 interaction. The details of these calculations are described in [17] and closely follow those of the GT strength except for the ∆T z = 0 character of the M 1 operator.…”

“…The study carried out in [17] for several isotope chains showed that the M 1 strength depends on deformation, not only for orbital but also for spin excitations. Thus, on general grounds, one may argue that the deformation dependence of the GT strength discussed earlier should be comparable to that of the spin M 1 strength considered in [17]. This is expected to be particularly the case when N = Z.…”

Gamow-Teller strength distributions in Xe isotopes

“…This is the path followed in our paper. This path has proven to be successful for studying the properties of the ground state and low-spin excited states in open-shell nuclei [12,14,23,25].…”

Low-energy dipole modes in the heavy deformed nucleus154Sm via inelastic polarized proton scattering at 0°

“…While some calculations suggest an explanation based on a separation of the proton and neutron 1p-1h states, others explain it as a separation into isoscalar and isovector strength [5][6][7][8].…”